Fuel-briqueting plant and the like.



T. RIGBY.

FUEL BRIQUETING PLANT AND THE LIKE.

APPLICATION FILED FEB- 16. 1912.

Patented Dec. 12, 1916.

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m 1 mg T. RIGBY.

FUEL BRIQUETING PLANT AND THE LIKE. APPLICATION FILED FEB. I6, 1912.

1 98,658. Patented Dec. 12, 1916.

4 SHEETS-SHEET 2.

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Illlll l T. RIGBY.

FUEL BRIQUETING PLANT AND THE LIKE.

APPLICATION FILED FE B.16. 1912.

Patented Dec. 12, 1916.

T. RIGBY. FUEL BRIQUETING PLANT AND THE LlKE.

APPLIATION FILED FEB.I8.191Z.

Patented Dec. 12, 1916.

4 SHEETSSHEET 4.

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' 'wn'rcmomzme murrnn, or LONDON, ENGLAND.

. runn-nmeunrmernmrnnnrfin LIKE.

Specification o1. Letters Patent;

" Patented Dec. 12, 1911.6,

' upplication flled time 1c, 1912. Serial no; 677,928.

To all whom it may. concern Be it'known that I, Tnoims RIGBY, a

subject of the King of. Great-Britain and Ireland, and residing at Station Hotel, Dum'fries, Scotland, have-invented certain new and useful Improvements in and Relating-to Fuel-Briqueting Plants and the like, of which the following is. a, specification.

This invention relates to the drying, conveying and superheating of fuel in briqueting plants or similar installations and particularly to those installations in which fuel contaimng' a substantial percentage of water is' dried prior to briqueting.

It has been found in practice that-the material (which is usually dried, in the type of drier known as .the Schultzei drier is highly inflammable whendry, and. it is therefore necessary to take precautions to avoid explosion. is particularly the case when treating lignite or brown coal and in a lesser degree .when'treating peat. In such processes it is usual to disintegrate the fuel in the-first place while still moist, e. g. containing 50 to. 60per cent. by weight-of passed through driers as indicated. The

through the driers' and carries away the water vapor given oif bythe fuel. The saturated air then passes to waste, the disintegrated dry material fallinginto' aconveyer or the like generally of the spiralkind whereby it is taken to abriqueting press.

of air and vapor is usually about 80 -C-.. in lignite factories,.but in this mixture .ccmbustion of the disintegrated fuel can occur. One object of the present invention is to overcome the'danger of ignition; a further object being to prevent the escape ofdust from the apparatus, which is a source of danger as it collectson the; walls and in crevices in the factory building. 4

A further obJect is to effect heat econom in a process ofthe character indicated.

This invention consists, in'eifecting the drying of the disintegrated. materialin an atmosphere incapable of allowing ignition, for example by reducing very considerably the air allowed to enter the driers to mix with the, disintegrated dusty substance and producing thereby a verywet atmosphere,

or by employing other inert gases such as flue gases entirely or partially to replace "the air.

This invention further consists in conveying the material to the briqueting press or other locality in an atmosphere of the character referred to, e. g. a mixture of water vapor and air or flue gases as above referred to and preferably obtained from the drying apparatus may. be employed or the material may be conveyed in an atmosphere of prod-.

nets of combustion alone.

. This invention also consists in efiecting final drying of the material or superheating of the same or both by the use of hot products of combustionwhereby these' operatlons. can be economically and safely carried out. p r

This invention also consists in the combination with a drier such as a Schultze :drierof. a suitable duct, exhauster and dust separator, so that material from the drier can be conveyed to the press or other locality in an atmosphere of the character indicated without escape of dust. water, and the disintegratedmaterial is then This invention also consists in the improved methods and apparatus for drying,

: sectional elevation and in part sectional plan an installation in which the material is conveyedby a very humid air current' Fig. 3 shows in part. sectional elevation a form in which conveyance is effected by products of combustion from some suitable source, and Fig. 4 shows a. form of the installation shown in Figs. 1 and-2 in which products .of. combustion are passed through the'drier itself.

Referring to Figs-1 and 2,-a a are rotary driers on the Schultze type,- in which a shell a rotatable by means of the toothed ring a between the two end pieces a a, carries by means of end tube plates, a plurality of tubular conduits a, through which the material to be dried in association with some air or other gaseous mixture admitted at the end of piece'a passes, due to the tumbling motion resulting from therotation of the ated by belting from the shaft 6. The driersare provided with safety relief tubes f, with suitable weighted doors, g, and are at their inlet ends either practically totally inclosed to prevent ingress of more than a little air, or are provided with means for closing the inlets to a' regulated extent to limit the amount of air entering as desired. At the same time, it-is desirable to provide a mica window 72, in the end cover of each drier to allow of inspecting the tubes as the drier rotates to ascertain that all are free from stoppages. The outlets i of the driers depend into a closed trough k in which is a screw conveyer Z which feeds the material to the intake of a fan m. A duct, n, is provided to lead steam or moist air in any desired amount to the intake of the fan. The fan gathers up the light dusty powder and conveys it through the duct 0, leaving behind all stony matters which are separated out by a stone separator, and pass into a pit .g. The duct 0 is surrounded by a steam jacket 1-, into which steam say at 2?; atmospheres pressure is passed to prevent condensation from the humid current passing through the duct, and this jacket is provided with abundant lagging 8. Steam traps t are provided in connection with the jacket. The duct 0 opens into a cyclone 'w situate above and opening into the bunker o. 'The gas duct 3 from the cyclone passes to a fan 1, which through a dust separator 2' is connected to the gas outlet of the installation.

The bunker 'v is jacketed and lagged like the duct 0, and feeds the material as and when desired and after any necessary superheating into anopen die briquet press 2.

The installation is operated as follows The material which passes through the heated driers a is dried therein, and by al-.

lowing little or no air to pass through'the drier the atmosphere in contact with the material can be caused to become so humid therein that no possibility of ignition can arise. The mate-rial still in such an atmosphere is by the conveyer Z brought to the intake of the fan m, where the light dusty particles are drawn by'the velocity of the gas current-through the duct 0 into the cyclone, the heavier stony matters remaining behind and passing out to the pit g. In the cyclone w the solid matters are precipitated and fall into the bunker 2), while the mixed air and water vapor after the separator z are sucked of the dry material;

passing through V out by the fan 1- andpassed out to any suitable spot and preferably to the grate of the ammonia recovery producer where such is used in the plant to utilize the larger amount of water vapor therein contained, The material which has fallen into the bunker is in the usual wa superheated and supplied to the briqueting press 2.

Referring to Fig. 3', the same shows an installation of the nature of that last described, but in which products of combustion from any suitable furnace are supplied to the fan m to convey the material? In this case the dried material which is collected from the driers is passed by the conveyer to a tube 3 in which is a distributing arrangement 4, which delivers the material into a closed ended flue 5, into-which the flue gases are introduced and into which the intake (5 of the fan m opens. Steam jacketing around the duct 0 and bunker a may in this case be dispensed with. J

In Fig. 4 is shown an installation of the nature of that described in connection. with Figs. 1 and 2, modified so that a cer-' air as may be necessary can be admitted tothe intake of the fan as referred to in connection with the installation shown 1n F1gs. 1 and 2, and such a method is of particular advantage in connection with thebriqueting of lignite, which is particularly dangerous. In an arrangement as shown in Fig. 4. and operated as indicated, at no stage is "there a sufficiency of oxygen present in the atmosphere in contact with the material to lead to any risk of ignition.

It willbe understood'that' th m'aterlal may be transmitted by suction. through the driers, a'suitable exhausterorequivalent arrangementbeing applied to the gas outlet of the cyclone or other separator for this purose.

p The speed of the gaseous atmosphere in the duct from the drier must in all cases be sufficient to carry forward the dr material,

and the velocity should be varie therefore according to the specific gravity and nature When using systems as indicated in Figs. I

1-3 it is desirable in every case to admit a liimted quantity of air into the driers, as the difiiculty of avoiding condensation is thereby considerably reduced.

Hitherto difliculties have arisen in the ef. fective separation of the light dust from the gases leaving the drier, but by reducing according to the present invention the amount of air in the mixture which leaves the drier, the specific gravity of the mixture is reduced and thedifl'erence between the specific hood of 95 C. (corresponding to about 10' gravity of the mixture and of the dust is thereby increased, and separation by a cyclone or other device is rendered easier.

When working with lignite or brown coal it is in some cases necessary to reduce the temperature of the dust to the neighborhood of between 30 and 40 G.,j,-hefore briqueting, which may be efiectedin any suitable manner.

Although the substance leaving the driers has been referred to as dried material, it will be understood that the actual water content may vary-considerably, being with' some fuels as much as 15 per cent, while with peat only a very small percentage, e. 1171., t e

'2 or 3 per cent. may be contained in j material when itl It will be understood that the higher the eaves the driers.

saturation temperature which can be employed for the air and vapor mixture, where such is the mixture employed, the more re mote is the possibility of ignition and the higher the temperature which the material can be caused to have when it is separated from the stream of mixed air and steam.

When working with peat, a saturation temperature for the mixture in the neighbor- Byutilizing for theheating products of combustion which are composed practically wholly of inert gases the danger of explo-- sion during the process is reduced to a m1m--' mum, and as these gases are usually waste products, by utilizing the same economy in the heat supplied is obtained. By effecting drying and heating by a gaseous heating medium which comes into direct and intimate contact with the particles of the substance, a relatively far greater efiiciency-is obtained than where the material is heated in bulk from external sources.

Although the methods described with refonly.

erence to Figs. 3 and 4 present advantages with respect-to effecting superheating while convefalying the material, and economy due to the gases being waste products, the method indicated with respect to Figs. 1 and 2 is to be preferred, as it involves a lesser alteration of existing installations, and the Waste gases (humid air) can be utilized in the manner previously indicated.

....It will be seen that by operating according to the present invention, dangerous dust 1n the factory can also be almost entirely obviated, while at the same time if any tendency is observed for air to leak into the apparatus, the steam pressure may be adjusted so as to overcome the same. V

It will be understood thatthe present invention may be carried into efiect in many difl'erent ways, and that the methods above described are referred to by way of example Having thus described my invention what I claim as new and desireto secure by Letters Patent is 2- 1. The method of reducing the liability of fire in a briqueting installation in which an inflammable powder, for the purpose of removing moisture therefrom, is normally passed through a drying apparatus in association with a gaseous mixture having constituents tending to support combustion, such method consisting in reducing such constituents beyond the point at which inflammation canbe propagated throughthe associated mass.

2. In a briqueting installation in combination, a drier, means for supplying a limited alantity only of gas to said drier to assist e removal of moisture from powdered peat undergoing desiccation, an element for separating solids from gases, a duct connecting the locality at which the drier is situated to said element, a duct connecting the outlet of the drier to the former duct, and means for causing a rapid stream of non-inflammable flue gases to flowthrough the former duct, I

as set forth. 1

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

f 'r. RIGBY.

Witnesses: J AMES W. GREEN, BERTRAM H. Ma'rrnnws. 

